The production of Group II and Group III base oils employing hydroprocessing has become increasing popular in recent years. Catalysts that demonstrate improved isomerization selectivity and conversion are continually sought. As discussed in U.S. Pat. No. 5,282,958, col. 1-2, the use of intermediate pore molecular sieves such as ZSM-22, ZSM-23, ZSM-35, SSZ-32, SAPO-11, SAPO-31, SM-3, SM-6 in isomerization and shape-selective dewaxing is well-known. Other typical zeolites useful in dewaxing include ZSM-48, ZSM-57, SSZ-20, EU-I, EU-13, Ferrierite, SUZ-4, theta-1, NU-10, NU-23, Nu-87, ISI-1, ISI-4, KZ-1, and KZ-2.
U.S. Pat. Nos. 5,252,527 and 5,053,373 disclose a zeolite such as SSZ-32 which is prepared using an N-lower alkyl-N′-isopropyl-imidazolium cation as a template. 5,053,373 discloses a silica to alumina ratio of greater than 20 to less than 40 and a constraint index, after calcination and in the hydrogen form of 13 or greater. The zeolite of 5,252,527 is not restricted to a constraint index of 13 or greater. 5,252,527 discloses loading zeolites with metals in order to provide a hydrogenation-dehydrogenation function. Typical replacing cations can include metal cations, e.g., rare earth, Group IIA and Group VIII metals, as well as their mixtures. Of the replacing metallic cations, cations of metals such as rare earth, Mn, Ca, Mg, Zn, Cd, Pt, Pd, Ni, Co, Ti, Al, Sn, Fe and Co are particularly preferred. A method for preparation of MTT-type zeolites such as SSZ-32 or ZSM-23 using small neutral amines is disclosed in U.S. Pat. No. 5,707,601.
U.S. Pat. No. 5,397,454 discloses hydroconversion processes employing a zeolite such as SSZ-32 which has a small crystallite size and a constraint index of 13 or greater, after calcinations and in the hydrogen form. The catalyst possess a silica to alumina ratio of greater than 20:1 and less than 40:1.